It is narrated from Sayyiduna Ma'mar bin Abdullah 'Adawi (may Allah be pleased with him) that he sent a slave to take one sa’ of wheat, sell it first, and then buy barley in exchange for it. So the slave went and brought back more than one sa’ of barley. When he came to Sayyiduna Ma'mar (may Allah be pleased with him) and informed him about the transaction, he asked: Did you really do it this way? Go back and return this transaction, and take only equal for equal in exchange, because I heard the Messenger of Allah (peace and blessings be upon him) say that when selling grain for grain, it must be equal for equal. At that time, our food was barley. Someone said: But these are not of the same kind. However, Sayyiduna Ma'mar (may Allah be pleased with him) said: I fear that it may resemble it (i.e., riba/usury).

Abu Dahana narrates: He says, I was sitting with Sayyiduna Abdullah bin Umar (may Allah be pleased with him), and he said that a guest came to the Messenger of Allah (peace and blessings be upon him). He said to Sayyiduna Bilal (may Allah be pleased with him): Bring food for us. So he went and gave two sa’ of dates and in exchange took one sa’ of good dates, as their own dates were of inferior quality. The Prophet (peace and blessings be upon him) liked these dates very much. So he (peace and blessings be upon him) asked: Where did these dates come from? Sayyiduna Bilal (may Allah be pleased with him) said: He took one sa’ of these dates in exchange for two sa’ of ours. The Messenger of Allah (peace and blessings be upon him) said: Return our dates.

It is narrated from Sayyiduna Abu Sa'id Khudri (may Allah be pleased with him) that fresh and juicy dates were brought to the Messenger of Allah (peace and blessings be upon him), while his own dates were of the Barani type and had become dry. Therefore, the Prophet (peace and blessings be upon him) asked: "Where did these dates come from?" The people said: "We exchanged two sa' of our dates for one sa' of these dates." The Prophet (peace and blessings be upon him) said: "This transaction is not correct. First, sell your own dates separately, then fulfill your need for this type with the price you get."

Narrated by Sayyiduna Abu Sa'id Khudri (may Allah be pleased with him): He said, "During the time of the Prophet (peace and blessings of Allah be upon him), we used to be given mixed dates, so we would give two sa' of them to buy one sa' of good dates. But when this reached the Prophet (peace and blessings of Allah be upon him), he said: 'Two sa' of dates for one sa' is not allowed, nor two sa' of wheat for one sa', nor two dirhams of silver for one dirham.'"

Narrated by Sayyiduna Abu Sa'id Khudri (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) distributed among them such grain that some of it was better than the other. Because of this, we began to sell it among ourselves with an increase and decrease, but the Messenger of Allah (peace and blessings be upon him) forbade us from making such a sale, except that it should be equal in measure and there should be no excess on either side.